In Bureau of Heilongjiang Agricultural Reclamation Department Sanjiang Branch, a 35 t/h cir­culating fluidized bed boiler of a thermal power plant burns the mixture of coal and rice husk instead of burning the original bituminous coal. It was found that the boiler saves about 20-40% coal. In the boiler, nearly 200,000 m3 of straw were burned every year and saved the cost of coal about 2.1681 million Yuan (Wang, 2004). The branch has a rice planting area of about 1.6665 billion m2, with a rice output of 1.25 million tonnes per year. The thermal power plant had done a lot of research work in how to utilize rice husk to combust mixed with raw coal. As a result, a new way was found that a small and medium-sized circulating fluidized bed boiler is used for producing heat and generating power with co-combustion of coal and rice husk. The information on the boiler is shown at Table 4.7.

In the plant, coal is conveyed piecewise with a belt. Rice husk is transported by air conveying, which is monitored automatically by limit switches.

Under a condition of the same coal and the same boiler output, comparing with pure coal, the boiler using co-combustion of coal and rice husk could save coal amount between 20-40% (average heat of coal Q„et. v.ar = 18,924,135 kJ/kg). According to coal consumption of 6078t/h with a boiler rated evaporation capacity of 35 t/h, it can be calculated and obtained that the average coal-saving amount is 1823kg/h and the coal-saving amount is about 43.8t/d (lower calorific value of rice husk, Q„et. v.ar = 14,785 kJ/kg; density is 8-9. 26 m3/t, the moisture content of rice husk is 12-18%). If the plant works 11 months per year, the coal-saving amount is 14,4541. Annually it could save the cost of raw coal is 2.1681 million yuan with the average price of coal is 150 yuan/t. In environmental protection, the plant has burned nearly 200,000 m3 rice husk per year, which realizing the transformation of waste to treasure with significant social and environmental benefits.